Variable speed power transmission



21, 1937. Y M ET AL 2,102,635

VARIABLE SPEED FOVHTIR TRANSMISSION Original Filed March 3, 1933 2 Sheets-Sheet 1 w I g mgons a i {Q I BY 40/1" I Dec. 21, 1937.

A. LYSHOLM ET AL VARIABLE SPEED POWER TRANSMISSION 2 Sheets-Sheet 2 Original Filed March 3, 1933 Patented Dec. 21,1937 l I 3 UNITED STATES? PATENT orrics VARIABLE SPEED POWER TRANS SSION Alf Lysholm, Fred Horney, and Giista Wahlsten, Stockholm, Sweden, assignors to Aktiebolaget Ljungstroms Angturbin, Stockholm, Sweden, a r corporation of Sweden 1 Original application March 3, 1933, Serial No.

659,500. Divided and this application November 21, 1934, Serial No. 754,080. In Germany January 14, 1931 e Claims. (or. 60-54) This application is a division of our copending 'draulic power transmitting mechanism is mountapplication Serial .No. 659500, filed March 3, ed as by means of ball bearing l2 and journal 1933, and assuch is a continuation in part with bearing l3atthe central longitudinalaxis of the r respect to our application Serial No. 585,440 filed transmission within the casing Ill. Member M d January 8,1932, which has matured into Patent comprises a hollow shaft part l5, this part being No. 1,900,119 granted March '7, 1933, and relates the part journalled in the bearings, and a disc-like back as to all-common subject matter for all dates impeller'part I6 located within the chamber I I and rights incident to the filing of said applicaand carrying a ring of impeller or pump blades I'I,

' tions Serial Nos. 659,500 and 585,440. the axially inner ends of which arejoined by an The present invention relates to variable speed annular ring l8. At its forward end the shaft power .transmissions and has particular referpart l of theprimary member has splined there'- ence to variable speed power transmissions of the to a clutch plate IS. The secondary or driven type in which hydraulic variable speed mechamember of the hydraulic power transmitting nism is combined with mechanical power transmechanism comprises a hollow shaft part 2| romitting mechanism to provide for automatic vari-. tatably mounted in co-axial alignment with able speed ratios and positive direct drive to a shaft part l5 of the primary member and supdriven shaft. ported in'housing H] by ball bearing 22. Mem- In its several phases the invention aims to imber 20 also comprises an impelled or turbinepart prove upon transmissions of the above stated 23 situated in chamber H, and comprising a discgg character, particularly with respect to features like portion carrying a ring'of turbine blades 24,

of construction of the hydraulic variable speed which at'their inner ends are joined by and supmechanism whereby such mechanism is made port an annular ring 25. Ring 25 extends radimore advantageously usable in a structure emally outwardly from theportion attached to bodying the feature of direct mechanical drive, blades 24, and at its outer part hasan axially g7, and whereby the hydraulic mechanism may be extending circular flange 26 which supports a more compactly and advantageously employed ring of radiallyextending turbine blades 21, the than in prior forms of construction. 1 outerends of which extend to within a short dis- With the above general and,other and more tance of the casing l0. Between the rings of specific aims in view, which will appear more turbine blades 2'5 and 24 there is situated a ring I in fully in the ensuing description, the invention of stationary guide-blades 28 secured at one end consists in the novel structural parts and com to ring 29 which is bolted to casing l0 and at binations defined in the appended claims. 1 their opposite ends to annular ring 3|] situated For purposes of illustration, we have shown the in a recess in the part '25. invention in several practical embodiments of The axially inner" end of the hollow shaft part 3., transmission structure suitable. for carrying the IB of the driving member is enlarged to provide invention into effect, and in the several drawan internal pilot bearin'g3| for the journal proirigsi vided by an axially extending bearing part 32 Fig. 1 is a central longitudinal section partly affixed to the inner end of shaft part 2|. Prefelevation o a an mission embodying the in erably, the impelled or turbine part 23 is keyed in vention; to the shaft part 2| and the bearing part 32 is 1 Fig. 2 is a similar section on a, larger scale of secured on the end of shaft part 2| as a locking the hydraulic portion of a transmission of the member, suitable packing being provided between same general character as that illustrated in parts 2| and 32 to prevent leakage of operating fluid therebetween from chamber Between Fig. 3 is a section on a still larger scale of part the part 32 and the hollow shaft part I5 packing of the structure shown inFig. 2; and is provided to prevent flow of fluid which may Fig. 4 is a central-longitudinal section of part pass bearing 3| to the space within the hollow of the hydraulic mechanism of still another emshaft parts. This packing means comprises in bodiment of the invention. the present embodiment apacking ring 33 affixed Referring now to Fig. 1, the transmission illusto the shaft part l5 and having a radially extrated therein comprises a casing I0 adapted to tending face against which a packing ring 3 be non-rotatably mountedin the frame of a v abuts. Ring 34 is pressed against ring 33 by hicle or the like and providing a main annular means of a coil spring 35 locatedbetween ring chamber II for circulation of operating fluid. 34 and part 32, and the spa The primary or driving member It of the hyis sealed by means of an expansible bellows memce between these parts 1 ber 36 attached to the parts. Similar packing means is provided between the journal bearing I3 and bearing l2 This packing means comprises a bearing ring 31 affixed to the shaft part videdbetween the driven member and the bearing 22 supporting the shaft part 2 I. This packing means comprises a packing ring 4| fixed to shaft 15 2| and a cooperating packing ring 42 pressed /against ring 4| by means of spring 43 located between ring 42 and a stationary tached' to the casing. The space between ring these parts. I

Extending through the bore provided by hollow shaft parts l and 2| is a shaft 46, supported at itsforward end in ball bearing 41 and at its rear- 25 ward endin a ball bearing not shown. Adjacent 52, which is axially shiftable with respect to the fly-wheel, but not rotatable with respect thereto.

'40 An annular cover plate 53 suitably bolted to the fiy-wheel provides a clutch surface 54 on its inner face, and the fly-wheel provides a clutch surface 55 opposite surface 54. Ring 52 is shifted axially by means of a series of peripherally spaced axi- 45 ally extending pins 56 which project through the cover plate 53 and at their outer ends are pivoted fixed to an annular spring plate 66 which extends 50 radially outwardly from a ring 6| carried by ball bearing 62 and guided in a circular flange 63 on the cover plate 53. The inner race of bearing 62 is fixed to one end of a sleeve member 64 which stood that other clutch means maybe employed I 70 for effecting this function.

In the form of apparatus illustrated, it will be evident that one or the other of the two clutch plates H1 or 49'may be engaged by shifting the part 64 axially, the spring plate 60 and levers 75 ,51 providing a spring-pressed toggle mechanism 7 60 and the driven shaft'l! clutch plate 49 is shown as in engagement and 3 for maintaining either one or the other of the clutch plates in engagement between the clutch ring 52 and one or the other of surfaces 54 and 55. Part 64 may be shifted axially by any suitable form of shifting fork which may advantageously 5 the driven shaft 11, mechanism is provided which tion from the shaft part 2| to the member 80. Member 86 is fixed to the shaft 46. Between part W there is interposed mechanical means providing a reverse gear whereby motion transmitted to part 86 either by the shaft 46 or the shaft part 2| may be transtion to the driven shaft 11.

The specific form of construction of the reverse gear, of which any suitable type may be employed, is not a part of the present invention, nor is a scription of this portion of the illustrated mm bodiment has been omitted. I The operation of the mechanism in transmitting power from shaft 50 to shaft 11 is as follows.

In the position of the parts as shown in Fig. 1, the

direction through the 60 tends to turn more rapidly than part 2| in the so as to engage clutch plate I! and release plate to to rotate in its normal directiontof rotation more members of the hydraulic power transmitting mechanism'with hollow Ishaftparts co-axialiy rapidly than the partllli. Asin the case of direct drive through shaft 46 the driven" shaft 11 =may have motion transmitted to it in either the same or reverse direction from the part 80 through suitable reverse gear mechanism. Ob- \viously, if noreversal of the shaft 11 the part 80 ;'-may be'directly connected to shaft I'll, and theareverse mechanism omitted.

is required Turning now more particularly to the features ofconstruction shown in Fig, 1, it .will be observedthat by making the primary and secondary mounted, there is provided at the longitudinally central axis of the transmission a bore through which a shaft can extend for direct transmission of power from thesourceof power to the driven shaft of 'the'apparatus. By this arrangement both variable .speed hydraulic-drive and direct drive may be provided for a variable speed transmission which is substantially as compact and of as suitable form for installation in the usual automotive or other likevehicle as is ahydraulic variable speed transmission of the same "general type as that disclosed. Stated'in anotherway, the provision of major hydraulic parts comprising axially aligned hollow shaft parts permits the addition of a direct drive feature tobe used in conjunction with the hydraulic mechanism without material complication of or substantial change in the characteristics of the hydraulic mechanism-.- I i It will further be observed that by mounting the forward end of the driven member of the hydraulic mechanism in a pilot bearing in thedriving member, the main rotating parts of the hydraulic mechanism may be rigidly mounted within a comparatively short axially extending space, which in. the present embodiment is represented by the distance between the bearings I2 and 22. The driving member is held in alignmentbetween the'spaced bearings I2 and I3, and the driven member is held in alignment between the bearings 22 and 3 I. If it werenot for mounting the forward end of the driven'member in the pilot bearing, a second bearing rearwardly of bearing 22 would be required to hold this part in alignment and this would involve additional axial length of thetransmission. It will be appreciated that for automotive and like installations, the

saving in space is of material practical importance.

, It is evident that the efficiency of operation of the hydraulic transmission would be greatly impaired-by large clearances between the rotating members and the stationary casing parts, and also bylarge clearances between the adjacent parts of the relatively rotating driving and driven members. By mounting one of the members in 'a pilot bearing in the other it is evident that not only a relatively rigid mounting is obtained for the members with respect to the casing, but also relative movement of one member with respect to the other due to .wom bearings is minimized.

. This construction enables close initial clearances to be employed and materiallyassists in maintaining close initial clearances over long'periods of use. p

By means of the pilot'bearing and packing arrangements shown, any substantial amount of leakage of operating fluid from the chamber II through the hollow shaft parts is prevented.

It will further be noted that the arrangement shown provides for separation of the ball bearings from contact with these bearings may be adequately lubricated with suitable lubricating oil. The pilotbearing is preferably, as shown, a plain journal bearing, and adequate lubrication of this hearing may be obtained from the operating fluid .which is usually of a somewhat oily character. For example, we

have-found a most suitable and satisfactory operating fluid to be kerosene containing a small operating fluid so that.

quantity, such, for example, as about five per cent (5%) of lubricating oil. The journal bearing I3, however, may be lubricated from an external lubricator through the channel I27. Such operating fluid as may leak past the several packings to theinterior of thehollow shaft parts I5 and v2| is preferably kept from flowing longitudinally of the shaft parts by means ofsuitable hollow member I50. and a disk-like impeller part Ilia/carrying a ring of impeller blades Ila. The

driven member comprises a hollow shaft part 2Ia and a turbine part 23a, the latter carrying three ringsof turbine blades 21a, 24a and I28. The inner ends of the impeller or pump blades Ila. are attached to ring Illa, and the inner ends of turbite blades I28 carry ring member 2511, to which the blades 2la.and 24a are attached. The outer ends of blades 24a are secured to ring I30. Rings of stationary guide blades 28a and I3I are carried by the casing. The inner ends of blades I3I are connected by the ring 30a, situated in a suitable recess in the part 25a. It will be evident that as the operating fluid is circulated in a closed path of flow in the chamber Ila, it will tend to leak out from its confined path through the clearance spaces between the relatively moving ring parts and between some of these ring parts and the walls of the casing Ilia which, together with these parts, defines the path of flow. Suchjleakr age is detrimental to the efliciency of operation of the transmission mechanism, and in order to minimize this leakage we provide between the several relatively rotating parts cooperating projections and recesses which form in effect labyrinth packings providing substantial resistances to leakage flow. This construction is shown more clearly in Fig. 3 with respect to the part- 29a fixed to the transmission, which carries the ring of stationary guide blades I3I, and the rotating parts 23a and I30. Part- 29a is flanged at I32 and I33. and these flanges are recessed at I34 and I35 respectively. Parts 23a and I30 are similarly flanged, and the flanged portions are provided with recesses I36 and I31, which'cooperate respectively with recesses I34 and I35 to provide what may be termed labyrinth packings comprising a series of spaced annular clearances I38 and I39. The annular clearance spaces separated by the'recesses provide a tortuous path of flow for operating fluid, the nature of which tends to create turbulence in the flow of fluid and consequently minimizes leakage. Similar labyrinth packing is provided between other of the relatively rotating parts as, for example, as indicated generally at I 40 in Fig. 3.

It will further be evident that the operating fluid circulating in the closed path of flow in chamber IIa will exert an axial pressure on the parts I6a and 23a, tending to force them axial- 1y apart. This axial thrust is balanced to a considerable degree by the pressure of fluid in the spaces MI and I42 provided between the stationary casing parts and the parts I 60 and 23a respectively. Fluid under pressure enters space MI by way of clearance space between ring I 29 and the casing Illa, and fluid enters the space I42 by way of clearance space between the ring I30 and the casing Illa. In order to prevent this relatively high pressure prevailing in spaces I H and I42 from reaching the inner portion of the apparatus, labyrinth packings I43 and I44 are provided between parts I6a and 23a respectively and adjacent parts of the stationary casing structure. These packings comprise cooperating projections and recesses similar to those described above with reference to Fig. 3. It will be noted that there is a relatively large space I45 between the main casing and the radially inner .portion of the part 23a, and in order to minimize the losses due to turbulence of fluid in this space, a stationary baffie plate I46 is provided adjacent to 'the radially inner portion of part 23a. This baiiie serves to maintain the fluid in the space I45 in substantially quiescent state when the turbine member is rotating.

The pilot bearing arrangement in the present embodiment is different from that shown in Fig. 1. The driven member in this instance is rotatably supported in the casing by the ball bearing 22a. and the journal bearing I3a, the latter being formed in the stationary casing part I41. The turbine part 23a provides a cylindrical journal I48 for the pilot bearing I49 formed -in the annular extension I60 of the impeller part I6a. of the driving member. The driving member is supported by pilot bearing I49 and ball bearing I2a. It will be evident that this arrangement provides the same compactness axiallyof the .parts, and insures the same alignment ofthe' parts as the arrangement previously described in connection with Fig. 1.

As in the arrangement shown in Fig. 1, packings are provided between the casing and the driving and driven members of the hydraulic mechanism, and packing is provided between these members. The construction and arrangement of the packings is substantially the same asthat previously described, corresponding parts being designated by the same reference characters with the suffix a and need not again be described in -detail.

Fig. 4 illustrates still another embodiment of apparatus in which the driving and driven mem- Tbers of the hydraulic mechanism are mounted in plain journal bearings. The driving member I4b comprises a hollow shaft part liband animpeller part I61) and is. mounted in a plain bearing indicated generally at I15, in the casing I 0b. This bearing comprises a cylindrical bearing surface H511 and a radially extending bearing-surface I15b, so that the bearing provides not only radial .support for the driving member but also provides a surface for preventing axial displacement of this member.-- The driven member 20b is mounted in the casing in bearing I16, which has a cylindrical portion "Ga. and a radially extending bearing surface "6b. The shaft part II b of the driven member is provided with able area and also past leakage of operating a forwardly projecting annular extension I11 projecting into a suitable recess in the extension I18 of the driving member I4b. Extension I11 is joumalled in the drivingmember by. means of a pilot bearing,which .in the present instance comprises the spaced cylindrical bearing surfaces I19 and I80 and a radially extending bearing surface I8I provided between the driven member 20b and the axially extending extension I18 on the driving member. From the drawings it will be evident that the above described arrangement provides for holding the driving and driven members of the hydraulic mechanism in proper co-axial alignment with respect to each other and with respect to the axis of the casing, and also provides against axial end-play of the members both with respect to each other and with repect to the casing. In this arrangement, as in the arrangement previously described, packing is provided between the driving and driven members for preventing flow of fluid to the spaces in which the central shaft 46 is located. This packing, it will be observed, is in all the several em-- ing chamber of the transmission to the space in which the driving shaft is located must force its way serially past bearing surfaces of consider the packing, which may be said to be arranged in series with respect to. leakageflow. This minimizes the possibility of fluid from the main operating chamber at this point, and also minimizes the possibility of air passing to the operating chamber from the space around the central drive shaft under conditions of operation which might produce negative pressure of the operating fluid in the radially inner portion of the main cham- 'ber.. In the present embodiment packings of the type already described are provided between the hollow shaft parts I6b and 2Ib and the casing,

invention embraces all such changes and modifications in the apparatus herein illustrated by way of example, as may fall within the scope of the appended claims when they are construed as broadly as is consistent with the state of the prior art.

It will further be understood that certain fea- 'tures of the invention maybe used to the exclusion of others.

What we claim is:

1. In a variable-speedpower transmission, a casing providing a chamber for operating fluid, hydraulic variable-speed power transmitting mechanism comprising a driving member and a driven member, the driving member comprising a shaft portion, a hub portion and a disc portion located in said chamber and carrying a ring of impeller blades, the driven member comprising a shaft portion, a hub portion and a disc portion located in said chamber and carrying a ring of impelled blades, said impeller blades and said impelled blades being arranged to transmit power from the driving member to the driven member and said shaft parts beingin axial alignment, the exterior of said hub portions being shaped to define the radially inner part of a closed path of flow for the operating fluid, one of said hub said hub portions having a cooperating axial ber for operating fluid, hydraulic variable-speed ing chamber,

power transmitting mechanism comprising a driving member having a hollow shaft part rotatably mounted in said casing and an impellerpart in said chamber, a driven member having a hollow shaft part rotatably mounted in said casing and an impelled part in said chamber arranged to receive operating fluid discharged from said impeller part, said hollow shaft parts being mounted in axial alignment and providing an axially central passage adapted to receive a power transmitting shaft passing therethrough, a pilot bearing between adjacent ends of said driving and driven members and annular packing means between said driving and driven members, said packing means and said pilot bearing being arranged serially in the line of flow of leakage fluid passing from said chamber to the passage provided by the hollow shaft parts of said members.

3. In a variable-speed power transmission, a non-rotatably mounted casing providing a chamber for operating fluid, hydraulic variable-speed power transmitting mechanism comprising a driving member having a hollow shaft part rotatably-mounted in said casing and an impeller part in said chamber, a driven member having a hollow shaft part rotatably mounted in said casing and an impelled part in said chamber arranged to receive operating fluid discharged from said impeller part, said hollow shaft parts being mounted in axial alignment and providing an axially central passage adapted to receive a power transmitting shaft'passing therethrough,

a pilot bearing between adjacent ends of said.

driving and driven members and annular packing means between said driving and driven members, said packing means being located between said pilotbearing and said axially central passage.

4; In a variable speed power transmission of the kind in which power is transmitted from a driving shaft to a driven shaft by circulation or a working fluid in a closed path of flow; in a worka driven member having a turbine portion located in said chamber and a hollow shaft portion extending therefrom power tothe driven shaft, and a driving member including pumping means arranged to be rotated by the driving shaft to circulate working fluid in said chamber,

to transmit laid naving a hollow central portion in alignment with the hollow shaft portion of the driven member to provide an axially central passage for the reception of a power transmitting shaft capable of rotating at a speed different from the speed of either of said members and adapted to be connected to Y and driven from said driving shaft.

5. In a variable speed power transmission of the kind in which power is transmitted from a driving shaft to a driven shaftby circulation of a working fluid in a closed path of flow in a working chamber, a driven member having a turbine portion located in said chamber and a hollow shaft portion extending therefrom to transmit power to the driven shaft, anda driving member including pumping means arranged to be rotated by thetdriving shaft to circulate working fluid in said chamber, said driving member having a hollow central portion in alignment with the hollow shaft portion of the driven member to provide an axially central passage for the reception of a power transmitting shaft capable of rotating at a speed diiferent from the speed of either of said members and adapted to be mechanically driven from said driving shaft, and an annular pilot bearing between said members,

said pilot bearing having a diameter greater than 1 the minimum diameter of the passage provided by the hollow portions of said members.

6. In a variable speed power transmission of the kind in whichtpower is transmitted from a driving shaft to a driven shaft by. circulation of a working fluid in a closed path of flow in a working chamber, a driven member having a turbine portion located in said chamber and a hollow shaft portion extendingtherefrom to transmit power to the driven shaft, and a driving member including pumping means arranged to be rotated by the driving shaft to circulate working fluid -in said chamber, said hollow shaft portion of the driven member providing an axially central passage for the reception of a powertransmitting shaft adapted to be mechanically driven from said driving shaft and extending from said driving member through the hollow shaft portion of the driven member and capable of rotating at a speed different from that of said driven member, and an annular pilot bearing between said members; said pilot bearing having a diameter greater than the minimum diameter of the passageprovided by the hollow shaft portion vof said driven- 

